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skywatcher at 07:44 AM on 1 June 2011The Critical Decade - Part 1: The Science
I know I'm not Albatross, but I can see at least ONE statement that is clearly, false, Camburn... Camburn #102: " ... I shall not post to this thread in the future." Surely you don't need me to back up why it's false :) -
trunkmonkey at 07:42 AM on 1 June 2011CO2 only causes 35% of global warming
Dikran Marsupial @5. If I had said, "In the parts of the absorbtion spectra where CO2 and water vapor overlap _and where they exist together in the lower troposhpere_ water vapor seems to dominate the absorbtion and reduce the effect of CO2. The abundant H2O vapor is more likely to catch the photon down there, and if it happens to radiate another upward, that one also is most likely to be absorbed by H2O, and so on, like an Austraiian Rules football, until the game reaches an altitude where CO2 predominates and the photons are emitted at a lower temperature.", would you have believed I read the article? Connie Le Quere believes increased up and down welling caused by stronger and poleward migrating westerlies will reduce the oceanic uptake of CO2. An interesting article disagreeing with her at AAAS states a model run showed decreasing uptake to about year 2000 and increasing uptake thereafter. All of this presupposes that the westerlies increase. The recent trend toward polar warming may reduce the gradient that drives the westerlies.Moderator Response: [Dikran Marsupial] Yes, but that isn't what you wrote, and it is entirely irrelevant to the greenhouse effect that water vapour absorption dominates in the lower trophosphere, because that is not where the Earth's energy balance is determined. Had you written that, I would believe you had read the article, but not understood it. As for the ocean uptake, Le Quere is taking about the saturation of the oceanic reservoir, which (thankfully) hasn't happened yet, note the tense of "will reduce oceanic uptake of CO2". Try this paper (which is an anlysis of what has happened, rather than what is likely to happen), look at Fig 2d, which shows the oceans to be a sink, and that the sink has been deepening over the last 50 years. -
adelady at 07:11 AM on 1 June 2011If It's Not Sex, Drugs, and Rock 'n Roll, what is it? Creativity maybe?
Eric, Australia's cool, wet autumn. Apart from the dry and fire blackened West, yes, the last gasp of the now defunct La Nina has made it pretty cool and wet here. Nuclear annihilation a fear concocted by governments? Seems you weren't around for the Cuban missile crisis - now there's real fear. The "anti-state movement" was mostly a reaction against stifling socialconformity. The civil rights movement for instance was not anti-state, it was anti-particular-policies. It was revolutionary - in favour of replacing governments or policies - rather than anarchistic favouring no government activity at all. I see current circumstances in much the same light. Only now we're arguing for the rights of the too young to vote, the not-yet-born, and the never-voting animals and plants of the bio-sphere. -
scaddenp at 07:07 AM on 1 June 2011Are you a genuine skeptic or a climate denier?
"6. Therefore, humans are partially responsible for the increase in global surface temperature." And what science are you citing in support of your implied assertion that some other natural forcing that is currently also causing change? The natural forcings that changed climate in the past are going negative. -
Rob Painting at 07:04 AM on 1 June 2011Amazon drought: A death spiral? (part 2:climate models)
CW -"when will the next El Nino and La Nina occur?"
El Nino later this year."why would one believe we could predict "changes in Earth's atmospheric circulation, under rising CO2"
The changes supporting the climate models are already observed. Not ironclad by any means, but consistent with model projections. And if, as predicted,. El Nino occurs later this year then another major Amazonian drought will be likely. Temperatures in the equatorial Atlantic are already well above normal, if that continues then the drought will once again be exceptional. Lots of 'ifs', but should that scenario unfold, the mechanics of why will be loud and clear to readers of this series. -
pbjamm at 06:57 AM on 1 June 2011Climate Change Denial book now available!
tallbloke@70 Would you care to share you work with? I am sure all here would be interested in reading it. Perhaps it is on your blog. I took a quick look and lost interest when the first article was a complaint about censorship on this blog. SkS is the most evenhanded blog I have ever seen. You are allowed to have your say as long as you remain civil and on topic. Pretty simple for those actually interested in civil discourse. -
kampmannpeine at 06:52 AM on 1 June 2011Of Averages and Anomalies - Part 1A. A Primer on how to measure surface temperature change
Thank you John, this helps a lot in clearing up the Hansen-mechanisms ... Did you know about the activities of Gistemp (http://clearclimatecode.org/gistemp/)? -
les at 06:16 AM on 1 June 2011Climate Change Denial book now available!
58 - les As, in fact, I am a real scientist with a fondness for best practice; I felt compelled to follow up on my prediction. 100% on the money. Twice if you slow post 69 - although it follows automatically by recursion. -
JMurphy at 06:03 AM on 1 June 2011Are you a genuine skeptic or a climate denier?
Eric the Red wrote : "I am not sure about your difference between #2 and #3, but I would classify them on the high side and low side of climate sensitivity, due to the rather large range of scientific opinions on the issue." You seem to be suggesting that the minority view on low climate sensitivity should be accorded the same weight as the majority view on the higher figures, or as the average view (c. 3C for a doubling of CO2). Is that right ? If so, how would you advise someone wanting to take a scientific opinion, with regard to the history of life on earth, between, say, the 10,000 years of creation 'science' and the 4 billion years of evolution science ? -
Alexandre at 05:33 AM on 1 June 2011Database of peer-reviewed papers: classification problematics
barry at 01:24 AM on 1 June, 2011 It's a good idea, and Barton Paul Levenson has a very interesting list in those lines, including sensitivity estimates from Arrhenius 1896 until 2006. It even includes the statistical distribution:
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Bob Lacatena at 05:29 AM on 1 June 2011Are you a genuine skeptic or a climate denier?
75, Utahn, At this point, sensitivity is very, very, very unlikely to be as low as 2 per doubling. Anyone clinging to that as a hope is absolutely in denial, because if you'll admit to everything as far as a 2 per doubling, then how can you simultaneously ignore all of the evidence for 3+? How can you not be concerned about that? At the same time, our current warming is almost certainly being held down by anthropogenic aerosols. Lord help us when we clean up the air, or otherwise slow our emissions, and see what the real effects of CO2 are without the negative forcing from aerosols. And that day has to come. Some day fossil fuels will run out, with CO2 left in the air for centuries or millenia, while the aerosols fall out in years or decades. I feel sorry for anyone who is alive when that happens, and it sadly may well be my own daughter. -
Bob Lacatena at 05:25 AM on 1 June 2011Are you a genuine skeptic or a climate denier?
The deniers on this thread seem to be recasting the argument, as if the "proper" position is whatever lies between the two extremes. They then cast the extremes as "deniers" (people who simply claim nothing at all is happening) and "alarmists" (people who think the current situation is dangerous). By positioning alarmists in this way, the middle of the road becomes "well, it may be human, but it may not, and it may be dangerous, but maybe climate sensitivity is low, and anyway maybe it will all work out for the best and maybe warming will be good, but we really don't know all that much right now anyway, so let's all just wait and see." This is typical, core denial, in concern troll clothing. Admit to something, but always with pause and reason to hesitate. Gotta be careful here. Can't be hasty. I term an alarmist as anyone who exaggerates the science. There are very, very few of those (although I did see an obnoxious WWF commercial last night that claimed polar bears could be extinct in 50 years, and I treat that as unnecessarily alarmist, and a harmful advert.). I term a denier as anyone who thinks we don't know enough, or climate sensitivity is at all likely to be low, or that there is any reason not to take the real science very, very seriously. The middle of the road is not "skeptics." They are deniers trying to pretend to have a substantive position. The middle of the road is not "lukewarmers." They are deniers, trying to have it both ways (i.e. the science is right or partially right, but only to a small degree so we don't have to worry). The real middle of the road is the people on this site, the people who understand the science, and look further than this site for information, and actually understand what they read. On another vein, people who suggest that one should look at multiple sources for information are certainly correct, but if those multiple sources include inflammatory, politically oriented, and grossly unbalanced and misinforming sites like ClimateAudit, WUWT, and others... well, you're kidding yourselves. They're fooling you, and you're happily fooling yourselves. -
Charlie A at 05:21 AM on 1 June 2011Can we trust climate models?
Eric the Red, #80 "It appears to be a somewhat arbitrary approximation. I am not sure that it should be tied to the GHG forcings at all, .." Obviously it is arbitrary to move from instrumental observations and reconstructions for the 1880-1990 period and then for the more recent 1990-2003 period change to a fixed level of aerosol forcings for the AR4 and Hansen 2007 paper. It is even more striking that four years later, Hansen changes again and decides to use the -1/2 of GHG forcing for the simulations of Hansen 2011, rather than using instrumental data. I don't know the reason for either of the changes in methodology. Do we really believe that our measurement accuracy pre-1990 was better than we have in 2011? The thread topic is "Can we trust the models?" Perhaps the real question is "can we trust the data fed into the models?" or "can we trust the data used to tune the models?" Obviously different types of emission sources have different ratios between aerosol emissions and GHG emissions. There is a lot of difference between a dirty coal plant without scrubber and burning high sulfur coal than one with scrubbers and/or using low sulfur coal. OTOH, Willis Eschenbachs simulation of the CCSM3 model resulted in 0.995 correlation with just a simple 1 box model and using only the solar, volcano, and GHG forcings. If aerosol forcings were large and uncorrelated, he could not have gotten those results. Hansen's 2001 senate testimony shows yet another version of forcings used by GISS. Note how the GHG and aerosols seem to be close to linearly related. Also of interest is the relatively low levels of aerosol forcings compared to GHG forcings. It is much less than the -0.5 factor now being used.
Caption: Fig. 3: Climate forcings in the past 50 years, relative to 1950, due to six mechanisms (6). The first five forcings are based mainly on observations, with stratospheric H2O including only the source due to CH4 oxidation. GHGs include the wellmixed greenhouse gases, but not O3 and H2O. The tropospheric aerosol forcing is uncertain in both its magnitude and time dependence.
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Utahn at 04:55 AM on 1 June 2011Are you a genuine skeptic or a climate denier?
Sorry Eric, more directly to sensitivity, it could be less than 2 per doubling... -
Utahn at 04:53 AM on 1 June 2011Are you a genuine skeptic or a climate denier?
Maybe # 2 could be "in the likely range" for whatever emissions scenario one is talking about? Whereas #3 could be "below the likely range"? That way we the cutoff would be when someone feels warming will be lower than the lowest bound of what consensus scientific opinion projects it to be... -
CBDunkerson at 04:52 AM on 1 June 2011Amazon drought: A death spiral? (part 2:climate models)
No, I was drawing a parallel to show the flaw in ClimateWatcher's logic (i.e. 'we cannot predict weather therefor we cannot predict climate'). -
Charlie A at 04:40 AM on 1 June 2011Can we trust climate models?
79 Kevin C: "One possibility would be to test many possible forcing scenarios against the available data." If I understand the caption to Hansen 2011 Figure 1 correctly, the modified forcing values for 1990-2003 should be 1.3243, 0.2080, -1.3762, 0.2949, 0.9599, 1.2072, 1.2922, 1.3506, 1.4875, 1.5901, 1.6431, 1.6390, 1.6393, 1.6442 These differ from the NetF.txt values by about 0.07W/m2 in 1990, going up to a difference of 0.27W/m2 in 2003. -
Eric the Red at 04:38 AM on 1 June 2011Are you a genuine skeptic or a climate denier?
Utahn, Interesting categories, but I find them somehow skewed to your own belief system. No arguement about numers 1 & 5. I gather you count yourself in #2, realists, being aligned with the IPCC consensus. I am not sure about your difference between #2 and #3, but I would classify them on the high side and low side of climate sensitivity, due to the rather large range of scientific opinions on the issue. I think you are doing a disservice to those accept the warming effects of CO2, but disagree on the magnitude. -
apiratelooksat50 at 04:36 AM on 1 June 2011Are you a genuine skeptic or a climate denier?
Utahn at 71 I can tentatively agree with you, though it might be interesting to assign a temporal aspect to it. Most of my reservations stem from the predictions. -
Camburn at 04:30 AM on 1 June 2011The Critical Decade - Part 1: The Science
Albatross: Show me ONE statement that I made that is false. I had said that I wouldn't comment. On this one, I will. Once again, show me ONE statement that I made that is false.....and I want you to BACK up why it is false. As someone who proclaims to understand scientific queries, you must also stay within the parameters of my statements. Thank you. -
Utahn at 04:30 AM on 1 June 2011Are you a genuine skeptic or a climate denier?
Pirate, from your #65, I would have called you a "lukewarmer" as it seems you accept that human emitted C02 is causing some warming? Anyway, I think the point of John's article was that even being a "lukewarmer" or a "skeptic"(in your definition) involves denying a robust body of scientific evidence. So denial still applies doesn't it? How about these 5 categories: exaggerators (those exaggerating risk without scientific evidence); realists (in line with climatologist consenus); mildy in denial (equivalent to lukewarmers); strong denial(your skeptics); and complete denial (your deniers)? Realists would of course base there opinion on the consensus view of climate science...Something like the IPCC, perhaps? Not that people couldn't have somewhat different views on various pieces and various errors of the IPCC, but the overwhelming major findings of their exhaustive literature review etc... -
Eric the Red at 04:28 AM on 1 June 2011Amazon drought: A death spiral? (part 2:climate models)
CB, ARe you implying that we are in for cooler temps? More snow storms occur during colder winters.Response:[dana1981] IIRC, studies have shown that more snow tends to fall in winters of hotter years, actually. But this is decidedly off-topic.
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CBDunkerson at 04:06 AM on 1 June 2011Amazon drought: A death spiral? (part 2:climate models)
You are arguing weather vs climate. We can't predict every snowstorm (weather), but it is a good bet that there will be more of them in Winter (climate). Climate trends are comparatively much less chaotic than weather events. -
ClimateWatcher at 03:36 AM on 1 June 2011Amazon drought: A death spiral? (part 2:climate models)
"changes in Earth's atmospheric circulation, under rising CO2, is the primary cause of the modeled Amazonian die-back."
Since we cannot accurately predict changes in atmospheric circulation which occur naturally (when will the next El Nino and La Nina occur?), why would one believe we could predict "changes in Earth's atmospheric circulation, under rising CO2"? -
Eric the Red at 03:24 AM on 1 June 2011If It's Not Sex, Drugs, and Rock 'n Roll, what is it? Creativity maybe?
For some the activies were an escape from the harsh realities of the time. Some escaped a little too far, and never returned. I think part of the whole nuclear annihilation fear was a deliberate attempt by both governments to scare their citizens into blind obedience to tackle a common enemy. Vietnam seems to open the eyes of the masses to the real horrors of the time. That was certainly a different take on Joplin and Hendrix, and I cannot argue against it. Would the anti-state movement of the 60s be protesting for a state-run solution to global warming? An interesting ponder. On a side note adelady, I read some reports recently of an unusually cold autumn in Australia after the heavy rain of summer. Can you confirm or deny? Thanks. -
Eric the Red at 03:09 AM on 1 June 2011Can we trust climate models?
Charlie, It appears to be a somewhat arbitray approximation. I am not sure that it should be tied to the GHG forcigns at all, as many seem to react independently. This may have been to accommodate the large uncertainty. Kevin, I am not sure we can answer your question either individually or collectively. I think the GCMs are not constrained enough, as they tend to ignore the possibility that Tom brought up in #77; namely what are the planetary feedbacks (If any) that we be invoked when the climate changes exceeds a certain threshhold? I think you may have partly answered your question by bringing up the limits of the instrument record. -
Eric the Red at 02:55 AM on 1 June 2011Database of peer-reviewed papers: classification problematics
barry, That sounds nice in principle. However, the numbers could be skewed either way by a preponderance of papers surrounding a particular calculation or data. This could be further enhanced from a group of authors each pulishing a different version of the same paper as lead author. Finally, the results could simply be an indicator of someone's publishing abilities. -
MichaelM at 02:36 AM on 1 June 2011Ljungqvist broke the hockey stick
RyanStarr, just looking at the Hadcrut site shows that the difference in temperatures for the whole northern hemisphere over the last 100 years is over 1 degree. Robert Ways graph shows the 30-90°N decadal averages in the 1.1 degree range. The Hadcrut data is available if you wish to do your own graph. -
JMurphy at 02:30 AM on 1 June 2011Video on why record-breaking snow doesn't mean global warming has stopped
seeker25801, to find out how you have come to the conclusions you state, how about answering a few questions ? 1) Why do you say "maybe" to global warming ? 2) Why do you say "nah" to Man-made global warming ? 3) What are the two sides ? 4) How does the climate being "'dynamic'" and "ever- changing" prove that man is not affecting the climate ? 5) When did the "global cooling period" start, when do you think it will end, and what forces are causing us to come out of it ? Depending on your answers, discussion can be taken to other threads where your claims may already have been discussed. -
Ari Jokimäki at 02:25 AM on 1 June 2011An Interactive History of Climate Science
Thanks for the note on the American thinker paper. I changed it to "online article". The database is not complete and perfect in any sense. There most likely are plenty of mistakes. The interface for adding papers is such that it is very easy accidentally select wrong choice for example for media type. -
Pete Dunkelberg at 02:15 AM on 1 June 2011Database of peer-reviewed papers: classification problematics
Your very first word is "Database". I don't know if you mean that, or if you are using a spreadsheet. Even the latter may have several columns. A database can be relational and support complex retrieval queries. On another note, after the incrementing numerical key (having nothing to do with anything else) and after after Author, title, journal and date fields, peer reviewed (Y/N), topic (sensitivity, sea level, etc), I prefer this main denier classification: 0. none 1. It's not happening 2. It's not us 3. It will be good for us anyway - or we don't know enough to justify doing the obvious, or at least taking effecting action (namely, stop burning carbon) will be worse than roasting ourselves. Note that delayers are a major type of denier. 4. 1 and 2 5. 1 and 3 6. 2 and 3 7. 1, 2, and 3 8. Insane (for instance, greenhouse warming violates thermodynamics) There may still be related fields for specific arguments. -
apiratelooksat50 at 02:08 AM on 1 June 2011Are you a genuine skeptic or a climate denier?
From what got snipped at 65. I will leave out the stuff that may have been deemed inflammatory. In trying to apply terms to peoples stances on AGW I believe we have 5 camps. Alarmists and deniers are extremists and usually operate on emotion and are difficult to reason with. However, warmists, lukewarmers, and skeptics are more centrist and generally can have scientific discussions and are more reasonable. I consider myself a skeptic. -
rlasker3 at 02:07 AM on 1 June 2011An Interactive History of Climate Science
This is considered to be a peer reviewed paper opposing AGW? Found in the 2010 skeptic list. http://www.americanthinker.com/2010/09/climatism_redoubling_misguided.html -
CBDunkerson at 02:04 AM on 1 June 2011Ljungqvist broke the hockey stick
RyanStarr wrote: "I've googled and found other overlays too, they don't even come close to this result." Well, without you citing these other overlays we can't really determine what they did differently. One possible explanation might be that they could have used global temperature anomalies rather than just the 30 to 90 degree range of the Northern hemisphere like Ljungqvist and the HadCrut data in figure 2. Or they could have stopped the data in the 1980s. Or mixed up the baseline values the anomalies were computed from. Et cetera. None of which changes the fact that even Ljungqvist concedes current temperatures are higher than the MWP. Further, his results are largely within the error bounds of the original 'hockey stick' and thus confirm rather than 'slaughter' it's findings. -
Kevin C at 02:02 AM on 1 June 2011Can we trust climate models?
Absolutely! Here is the problem even with cross-validated statistics. If you start tuning things to improve your holdout set statistics, then you invalidate the use of the holdout set. And yet at the same time, we want to use a holdout set to establish the validity of a model - indeed to select among competing models. All you can do is be very careful about how many decisions you make on the basis of your holdout statistics. So we come back to my questions at #16 again, which are crucial to this discussion and yet we don't have anyone who has an answer: To what extent is the response of a GCM constrained by the physics, and to what extent is it constrained by training? Similarly, the forcings that are fed into the GCMs are the result of models of a sort too. In some cases (CO2) a very simple model with ample experimental evidence. In others (aerosols) not. In the absence of a clearer understanding of the models, how do we go forward? One possibility would be to test many possible forcing scenarios against the available data. But I'm already banging my head against the limits of the instrumental record. You can bring in paleo, but the chains of inference become much longer and the data less accessible to the lay reader. (It's certainly beyond my competence.) -
apiratelooksat50 at 01:50 AM on 1 June 2011Are you a genuine skeptic or a climate denier?
J Bob @ 68 "Getting all the info from one source does not seem like an objective approach." Exactly! And, to take it a step further, even if the source is a compilation of articles/papers/data more than one site should be used. -
Charlie A at 01:47 AM on 1 June 2011Can we trust climate models?
Eric the Red @75: "I agree that given accurate forcings, we can make accurate temperature predictions. Therein lies the main question: How accurate are our predictions of the forcings?" A main point of Hansen's recent whitepaper is that we don't know current forcings very well. The GISS-E model runs of 1880-2003 for AR4 and Hansen's 2007 paper used aerosol forcing data that was arbitrarily flatlined for the entire 13 year period of 1990-2003. In his recent whitepaper the model runs replaced that flatlined data with an approximation that set the sum of (aerosol + black carbon + indirect aerosol + snow albedo) forcings = -1/2 of (CO2 + O3 + strat. H20) forcing. I find this surprising, although it doesn't seem to have attracted much attention. People refer to tuning of model parameters, but it appears that a lot of the fitting, whether consciously or via observer bias, has been done with adjustments of the forcings. -
RyanStarr at 01:28 AM on 1 June 2011Ljungqvist broke the hockey stick
The rules forbid me from saying what I would like to say. The Hadcrut overlay is... not right. The abstract of the paper itself only suggests the late 20th century is likely the warmist. How does the author here then manage to show recent years as being > 0.5 C above the highest Ljungqvist peak. I've googled and found other overlays too, they don't even come close to this result. Decadal mean temperatures seem to have reached or exceeded the 1961-1990 mean temperature level during substantial parts of the Roman Warm Period and the Medieval Warm Period. The temperature of the last two decades, however, is possibly higher than during any previous time in the past two millennia, although this is only seen in the instrumental temperature data and not in the multi-proxy reconstruction itself.Response:[dana1981] The figure in the post is correct. Ljungqvist terminates the data in his paper at 2000, so that's probably where the overlays you found on Google terminate as well. However, NH land temps did not stop warming in 2000. Our figure is up-to-date and uses the correct data, as other commenters have noted.
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seeker25801 at 01:27 AM on 1 June 2011Video on why record-breaking snow doesn't mean global warming has stopped
Global warming: maybe. Man-made global warming: nah. I just wish both sides would tell the full story. Our climate is "dynamic". Ever-changing. We're coming OUT of a global cooling period so of course it's going to get warmer. And weather is NOT climate. -
barry1487 at 01:24 AM on 1 June 2011Database of peer-reviewed papers: classification problematics
Hey Ari, nice to see you posting here. ------------------------------------------------------------- I'd like to see papers centred around a value, like climate sensitivity, sea level trends or temperature trends. Eg, label a y-axis -2 to 12* (for climate sensitivity), and a vertical bar for each paper per the range each gives. So when a skeptic cites Lindzen climate sensitivity estimates, I can point to the graph that shows not only what outliers his estimate are and where the studies cluster, but how much work has been done. Skeptics pounce on a paper as if it's the final revelation, instead of one of dozens. That's the visual that I think will make the most impact. Seems like a lot of work, though. * I don't know what the range for climate sensitivity should be. I just made it up, like Eric did (I got you, ETR). -
J. Bob at 01:13 AM on 1 June 2011Are you a genuine skeptic or a climate denier?
actually thoughtfull(?), says “information you could have found by searching this very site - not even requiring a Google search”. Getting all the info from one source does not seem like an objective approach. You also say, “Good thing you didn't base your job on your post above - you would be unemployed!”. Actually, before retirement, I was Dir. of R&D for an international Co. But getting back to the discussion, what points do you disagree with me? -
DaneelOlivaw at 01:08 AM on 1 June 2011Database of peer-reviewed papers: classification problematics
It's a mess. One thing I would suggest is identifying those arguments that are most relevant to the global picture and only taking those into account. So, for example, any paper addressing the "polar bears" argument is not pro, against or neutral... it's simply irrelevant. Of course, there are some studies whose relevance may be disputed. Is a paleoclimatic study investigating the climate 10 million years ago relevant to current warming? Some could say that it is since it may tell us a lot about climate sensitivity, but how much is difficult to say. I think that, in the end, we need to proceed as a scientist and look at the issue from multiple perspectives. Use different classifications schemes, filters and inclusion criteria and see what they tell us. A more compelling case can be made if the same conclusion (most papers agree with AGW) arises from multiple lines of evidence. -
Tom Curtis at 00:58 AM on 1 June 2011Can we trust climate models?
Eric the Red @75: 1) The climate response to doubling CO2 is well constrained independently of the models, so the GHG component of the forcings are unlikely to be significantly in error; 2) This means the four degree plus predictions for BAU are fairly reliable; 3) Natural variability (short of catastrophic meteor impact or vulcanism) is constrained to be less than 2 degrees by the fact that mean global temperatures have remained in a 2 degree range (more probably a 1 degree range) through out the Holocene; 4) As 2 degrees is considered the upper limit for "safe" temperature increases, natural variability will not save us from the consequences of BAU (and are as likely to worsen them as to mitigate them); 5) Therefore for practical purposes, the models are reliable enough. Having said that, there is a slight possibility that increasing temperatures will reach a tripping point that will generate a significant negative feedback, thus saving our collective bacon. It is significantly less likely that it will reach a tipping point (or several of those thought to exist) which will greatly accelerate global warming. These possibilities are beyond the models (and our) capabilities to predict at the moment. For policy purposes they are irrelevant. Relying on these possibilities is like taunting Mike Tyson in the confidence he will have a heart attack before the blow drives your nose out of the back of your skull. -
CBDunkerson at 00:57 AM on 1 June 2011Are you a genuine skeptic or a climate denier?
apiratelooksat50 wrote: "6. Therefore, humans are partially responsible for the increase in global surface temperature." Too vague. Only the complete lunatic fringe argue that humans aren't responsible for any of the increase. The mainstream scientific position is that we are responsible for most of it. Your 'partially' could fall anywhere in between. -
Albatross at 00:47 AM on 1 June 2011The Critical Decade - Part 1: The Science
Ken First, you do not deny that Camburn misrepresented Hansen. Good, but then you go and say this: "It Camburn and I are cherry picking on short timescales - then we seem to be in the company of Jim Hansen." Not true-- and your accusation of cherry picking against Hansen is ridiculous and unfounded, or are you simply musing about scientific misconduct by one of the world's leading climate scientists? Hansen, as always, looks at the big picture and context, even when he might be looking at shorter periods of time to solve a problem (i.e., it is not cherry picking to look at ENSO, but don't try and use ENSO to claim that the the long-term warming in global SATs is because of ENSO like contrarians McLean et al. infamously tried to do). Also, as I explained above to your friend @97 above, and which fell on deaf ears, "Tamino has shown otherwise, but regardless Hansen and Sato are wisely most definitely are not using noise in the data record as a reason to claim that we are not facing a whole lot of trouble down the road if we continue along those path. So you have misrepresented Hansen's position." To do so, focus on the noise and then make grandiose claims about the big picture, would be foolhardy. This game of focussing on the noise in the climate system to claim that 'warming has stopped or slowed so there is nothing to worry about', or that the 'theory of AGW has been overturned' etc, is very old, and I for one am sick of "skeptics" playing that game. We can be playing that game circa 2100-- "Ooh global SATs slowed somewhat the last 5 years", meanwhile the planet will have warmed significantly between now and then. "The UCAR SLR chart which you seem loathe to discuss and is often quoted in these threads, covers the period 1993-2010 - all of 18 years inclusively." A strawman, and not true. I posted an image of the satellite altimeter data above @52. Now I do not know if advancing strawmen and demonstrably false statements is a valid form of debating...oh wait it is, it is called baiting and gish gallop, and techniques which are used liberally by self proclaimed 'skeptics' and deniers of AGW. The Australian Climate Commission's report was right on the mark. How inconvenient for the 'skeptics', yet more evidence that runs counter their ideas. No wonder they are scrambling to obfuscate and fabricate debate. -
CBDunkerson at 00:46 AM on 1 June 2011Can we trust climate models?
Eric the Red wrote: "Other forcings must also be included, although some will average out in the long term (i.e. ENSO)." ENSO is not a climate forcing. It is a redistribution of energy within the climate. The confusion likely arises in that climate sensitivity is often estimated as a 'surface temperature anomaly'. Since ENSO involves movement of energy between the oceans and the atmosphere it can impact surface temperature anomalies on a short-term scale. This differs from a climate forcing in that it is not actually increasing the total energy in the climate system... just temporarily adjusting the proportion of that energy in one part of the climate which we commonly use as an indicator since it is (relatively) easy to measure. -
apiratelooksat50 at 00:35 AM on 1 June 2011Are you a genuine skeptic or a climate denier?
AT at 50 What mitigation efforts do you propose? -
Tom Curtis at 00:34 AM on 1 June 2011Ljungqvist broke the hockey stick
1) Science moves on. This is a fact hated by deniers because it robs them of talking points. (Talking points, of course, because they lack valid arguments.) Thus in 1998, Mann, Bradley and Hughes pioneered an innovative technique to reconstruct past temperatures. It was innovative, so they had nobodies mistakes to learn from except their own, so they made a few minor errors. Further, they had limited data to work with, which also created problems. As a result they produced a reconstruction with insufficient multi-decadal variability. The scientists picked up on the mistakes (the scientists, not McIntyre and McKittrick whose criticisms where mostly either trivial, or wrong), and have produce better recent reconstruction, such as Mann 2008 shown above. Clearly the denier talking point that RyanStarr wants to ressurect doesn't fit well with that graph, so he goes on about it because talking points is all he has. 2) The original MBH 98 graph did not even cover the medieval warm period. Their follow on MBH 99 did, and shows medieval temperatures approximately equal to those shown by Lungqvist. It then followed a more or less straight line, with decadal but not multidecadal variation to approximately the temperaure shown by Lungqvist in 1850. Consequently it was not the MWP that was supressed by the limitations in MBH's first time efforts, it was the Little Ice Age. That, of course does not fit the denier narrative, so RyanStarr ignores it and goes on about the MWP. 3) As noted above, and by Lungqvist in his paper, Mann et al 2008 shows a very similar curve to Lungqvist. Indeed, Mann 2008 shows a slightly warmer MWP (0.32 vs 0.29 11th century mean) and a very slightly colder LIA (-0.18 vs -0.17 in the 17th century), thus showing greater variability than Lungqvist, and two years before him. Therefore if Lungqvist "slaughters" MBH 99 (the hockeystick), he arrives late on the scene and only manages to slay a corpse. The real action came two years before, when Mann "slaughtered" MBH 99. Again, that doesn't fit the denier narrative, so only Lungqvist gets credit in the denier rant. This of course beautifully illustrates my first point. Scientists, because they pursue truth, move on. Deniers because they are only using talking points to sow confusion, cling to those talking points regardless, leaving them not only wrong, but ten years out of date to boot. Cue more empty denier talking points from RyannStarr ... -
apiratelooksat50 at 00:34 AM on 1 June 2011Are you a genuine skeptic or a climate denier?
AT @ 50 [inflamatory stuff deleted] It did leave me uncertain as to where your confusion on my stance comes from. Let me state it again. 1. Global warming is real and happening now. 2. Global climate change is a naturally occurring phenomenon. 3. CO2 is one of the greenhouse gases and is partially responsible for causing the Earth's surface to be warmer than if it were not present. 4. Human activities have led to changes of the Earth that have resulted in alterations of the climate. 5. Some of those activities include the burning of fossil fuels that have resulted in the increase of CO2 in the atmosphere. 6. Therefore, humans are partially responsible for the increase in global surface temperature. 7. As good stewards of the environment we should: take reasonable and rational methods to reduce our dependence on natural resources (both renewable and non-renewable), develop and utilize alternative energy (wind, solar, geothermal, nuclear, hydroelectric, etc...) where econmically feasible to reduce dependence on fossil fuels, and practice conservation. That should be fairly clear to most readers.Moderator Response: [Dikran Marsupial] Inflamatory material snipped. Whatever the perceived provocation, please try to stay within boundaries set out in the comments policy. -
Eric the Red at 00:33 AM on 1 June 2011Can we trust climate models?
Tom, I agree that given accurate forcings, we can make accurate temperature predictions. Therein lies the main question: How accurate are our predictions of the forcings? Yes, we can control CO2. We can also control many other manmade factors. But, what is the normal range of natural variability? More importantly, what will be the natural response to an increase in CO2? Actually, the errors will compound. Given a climate sensitivity of 3 +/- 1.5 C/doubling, the uncertainy will increase as CO2 concentrations increase. Other forcings must also be included, although some will average out in the long term (i.e. ENSO).
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